Thiel CS 3.5 speakers

[Norman Nicolai]

 I just purchased a set of Thiel CS 3.5 speakers in need of restoration. They did not come with the equalizer that normally comes with the speakers.  The 3.5 is a closed port loudspeaker, and fromwhat I understand, that is a departure for Thiel loudspeakers. All the drivers work and the cabinets are in pretty good shape. I think the speakers were neglected and need a good cleaning more than anything else. I have not really listened to them yet, other than to determine that the drivers work. The woofer has a rubber surround, and the tweeter domes are dented, but they still work.

Anyone know anything about these speakers? Do I absolutely need the Thiel equalizer for them to work as intended?

 

[Aadams]

41 minutes ago, Norman Nicolai said:

Do I absolutely need the Thiel equalizer for them to work as intended?

No.  You could use a single good quality 12 inch sub woofer instead and the Thiel woofers would be less stressed than using the original electronic subwoofer/equalizer which operated below 70 hz.  

[frankmarsi]

 

Hi Norman,

A close friend bought a pair of these back in 1989 or whenever they first came out. He drove them with a single B&K 202 at 150 WPC. They sounded balanced but, that amp was such a muted hang-dog sounding amp it was slightly difficult to discern their actual sound quality. The amp was suffering from too little power. He went out and bought the B&K mono-blocks that offered more power but, to me those still lacked any excitement across the frequency spectrum. Overall (for me), the speakers reminded me of more powerful AR-2ax. Though they had wider dispersion and slightly healthier bass response combined with slightly elevated and a more natural midrange response. I did enjoy them more than the AR-2ax and heard no problems in the short times I listened to them and felt them to be an enjoyable and pleasant sounding speaker.

I’m not able to offer any further personal listening impressions because I didn’t listen critically often enough to form a more thorough opinion. However, I liked them enough to keep in mind for future purchase though, I never did.

This friend who owned them I’ve described before in this forum. He owned AR-11 in '78 and switched to JBL L-100’s and then bought the Thiels. After several years he sold them and repeated his original purchase and bought another set of AR-11’s.

I’ve included two links reviewing them. When Jim Thiel passed away in 2009 I felt the company would loose its direction and they did close their doors in 2018 AFAIK.

Overall, I did like them and wish you luck with them as they are still favored by many.

 https://forum.audiogon.com/discussions/thiel-is-officially-closed

 https://www.audiosciencereview.com/forum/index.php?threads/renovating-thiel-cs3-5-speakers.18978/

FM

 

 

 

 

38

[Norman Nicolai]

       

         "No.  You could use a single good quality 12 inch sub woofer instead and the Thiel woofers would be less stressed than using the original                                 electronic subwoofer/equalizer which operated below 70 hz."

Using the Thiel speakers with a subwoofer is definitely an option. I ran that idea past the knowledgeable guy who sold me the speakers and he concurred that the woofers would be less stressed if I did that. The counter to that idea is why bother with Thiels's if you're going to have a third source of sound. Isn't "Coherent Source" the whole idea behind Jim Thiel 's design and introducing a subwoofer into the mix erases the entire "Coherent Source" concept.

I've listened to the Thiels a bit more since my purchase and the bass is definitely lacking. They were designed to be used with the equalizer and they are nothing special without it, at least to my ears. I think frankmarsi must have heard them used with an equalizer since he was reasonably impressed. There are dedicated equalizers available on eBay and they range in price from $160 to $350, which makes me guess that the lower priced ones probably need work. The other option is to part them out. There is a robust market for Thiel speakers and crossovers since Thiel went out of business five years ago. Dedicated Thiel devotees have no source of replacement parts, especially drivers.  I would hate to part them out since I just don't like to do that to speakers. Besides, I think the low price I got from the seller was because I promised to restore them.

If anyone else has an opinion on Thiel's, either positive or negative, please post here. It will probably influence me to either purchase an equalizer or part them out., because right now, without the equalizer, they just don't impress me.

 

 

 

[JKent]

38 minutes ago, Norman Nicolai said:

on eBay and they range in price from $160 to $350, which makes me guess that the lower priced ones probably need work.

Well, the $160 w/ free shipping says it works. Ebay has a good return policy--if it's not as described (working) they'll refund your money. I'd go for it. btw, one just sold on ebay for $99 so it looks like prices are all over the map. DIsclaimer: I've never heard Thiels.

OTOH< I'd also do a lot of research if I owned a pair of those. Based on what little I did read, the 3.5s are some pretty high end speakers. Acoustic suspension. I'd say the dedicated EQ is essentially the same as the Allison Electronic Subwoofer. My DB-5 Tone Control (goes with the DB-1 preamp) has a selectable bass boost that may do something similar. The Thiel unit reportedly boosts bass below 70Hz. 

I do like Aadams's suggestion of a separate sub but using the bass EQ that was designed to go with the speakers makes sense. I did see some grousing about the quality of the EQ and apparently there was an outfit back in the day that modified them.

So many decisions.....

[JKent]

PS:

Here's a manual: https://www.manualslib.com/manual/327977/Thiel-Cs-3-5.html?page=2

This thread has a schematic for the EQ: https://www.diyaudio.com/community/threads/popping-noises-in-thiel-cs3-5-bass-eq.294911/

 

 

[Aadams]

1 hour ago, Norman Nicolai said:

Isn't "Coherent Source" the whole idea behind Jim Thiel 's design and introducing a subwoofer into the mix erases the entire "Coherent Source" concept.

Almost all of the coherence is in the tweeter and mid. 

I would try a working equalizer for $350.  A subwoofer with software management to simplify the blending at 70hz will cost a good bit more.   The specs say the Thiel equalizer provides bass boost that is almost flat down to 20hz.  Those are some special 10 inch woofers if they can take that kind of punishment but it also has a 40 hz cutoff.  At 40 hz, they have roughly the same extension as a Large Advent or AR 91.  The lowest note on a four string bass is 42hz.  5 string electric bass is 32hz.   Concert Grand Piano 28hz.

 

 

[genek]

Modern electronic music often goes to down to 20Hz. 

A 32' pipe organ can produce a C₀ note at 16.5Hz.

The 64' Boardwalk Hall pipe organ in Atlantic City, NJ can produce a C₃ note at 8 Hz (if you ever get a chance to hear it, go to the bathroom first).

[Aadams]

19 minutes ago, genek said:

Modern electronic music often goes to down to 20Hz. 

True.  If you have library of dubstep or trap music as well as esoteric pipe organ you need the right speakers.  Otherwise almost all music occurs above 40 hz and speakers that begin to roll off at 40hz are all that most folks need.

[Norman Nicolai]

"The 64' Boardwalk Hall pipe organ in Atlantic City, NJ can produce a C₃ note at 8 Hz (if you ever get a chance to hear it, go to the bathroom first)."

Ha! genek, your comment about using the bathroom first had me laughing out loud!

I've heard the pipe organ in Ocean Grove, NJ, but not the organ in Atlantic City. The organ in Ocean Grove is very impressive and it supposedly has "only" 11,000 pipes. The Atlantic City boardwalk pipe organ allegedly has over 30,000 pipes.

After reading you guys I'm leaning toward purchasing a Thiel equalizer. After all, I only spent $80 on the 3.5's, and besides both of the tweeter domes being pushed in a tad, they are in great shape. Oh well, in for a nickel, in for a dime I suppose....

So many decisions, indeed, Kent....

[JKent]

Don't know why I'm fascinated by this thread. I know nothing about Thiels.

FYI the tweeters are Dynaudio D28AF. You should be able to suck the domes out but you can also get replacement silk dome voice coils and rebuild them.

In this thread AK member baco99 wrote "One thing I may do is replace the rubber woofer surrounds. They feel a bit stiff to me. . . . The bass seems a little constrained and I think a more supple surround will solve the problem". Doesn't look like he used the Bass EQ. https://audiokarma.org/forums/index.php?threads/thiel-cs2-restoration-project.876216/page-2

btw, you wrote "I've listened to the Thiels a bit more since my purchase and the bass is definitely lacking". Just for giggles, maybe try reversing the speaker wires on one speaker. I know many of us have accidentally hooked speakers up out of phase 😉

 

[Norman Nicolai]

            "btw, you wrote "I've listened to the Thiels a bit more since my purchase and the bass is definitely lacking". Just for giggles, maybe try reversing the                speaker wires on one speaker. I know many of us have accidentally hooked speakers up out of phase 😉"

I did re-check the speaker wring, Kent, because I have made that mistake before and it turns out it was phased correctly.  Incidentally, I have an old tube receiver, a Sherwood S8000IV that has a "phase rev" switch on the front panel, and it only sounds correctly phased when the "phase rev" switch is engaged. Who knew?

Okay, so I went whole hog and purchased a Thiel equalizer that listed for $125 on US Audio Mart. I negotiated the price down to $100 including shipping and I'm expecting it delivered this week.

BTW, full disclosure. I should mention that my initial testing of the 3.5's where I was not very impressed was not especially thorough. The speakers were hooked up to a 40WPC Sherwood S-7450CP receiver. To reveal their best, the Thiel's require at least 100WPC and have the reputation of being an "amp eater" because of their power requirements and 4 ohm load. It should set up an interesting situation in my basement lab. Most of my equipment is low powered tube amplification. I only have one power amp capable of driving a 4 ohm load, a SS Mitsubishi DA-A10, and I currently have my AR-91's hooked up to it. The AR-91's replaced my stacked OLA's, so between the stacked OLA's, the AR-91's, the recently restored KLH 33's and EPI M50's, the addition of the new Thiel's makes for a very crowded basement. 

As Kent is fond of saying, "so many decisions..."

[Norman Nicolai]

As I have said in previous postings, my Thiel cabinets are in very good shape, but it looks like at least one of the speakers may have been stored without the speaker grills in place so that the drivers are dust covered. The woofer material is plastic with rubber surrounds and I’d like to clean the plastic woofer cones but Im not sure what to use. I’m a little paranoid of doing damage. Any ideas anyone?

The cone on the midrange driver from the same cabinet looks pretty dirty, too. I was thinking of vacuuming it without touching the cone with the vacuum nozzle.

 

My Thiel equalizer arrived Wednesday  by USPS and surprise…it’s non-functional! Luckily, the technician I bought the Thiel speakers from, Ben Hase, looked at it and diagnosed and repaired a minor problem overnight. It’s ready now, but I need to wait until after the Labor Day Holiday, on Tuesday, to pick it up from him.

BTW, if anyone is looking for an audio repair tech in the NJ/metro NY area, you might want to consider Ben. He works out of SkyFi Audio in Glen Rock, NJ on T-W-TH and out of Brooklyn the rest of the week. He previously diagnosed a problem and repaired a Sherwood S8000IV receiver, and I had it back in about a week. I am not endorsing anyone here, but I know how hard it is to find a reputable tech for vintage electronics. Here is Ben’s email and a link to his Instagram site in case you want to look into using him.

ben@novaluxstereophonic.com

https://instagram.com/novaluxstereophonic?igshid=MzRlODBiNWFlZA==

 

 

[Aadams]

I thought you would have an answer by now.  Those Poly cones and rubber surrounds can be damp wiped with soap and water solution on a sponge.  First I would use a vacuum cleaning brush if you have it, instead of a nozzle. Back up would be a soft bristled paint brush to stir up the dust sucked into a vacuum nozzle held at a safe distance . I wouldn't touch domes or dust covers on drivers because they appear undamaged. For the bent tweeter dome I would first try to gently, persistently, pull it out with premium duct tape.  The premium tape is much stickier.

[JKent]

Good advice. You can also suck out the domes with a vacuum. Scary but it works. If the dome is paper and badly creased you can wet it first. I’ve done that with KLH 12.5 mid/full range drivers. 

[Norman Nicolai]

"Those Poly cones and rubber surrounds can be damp wiped with soap and water solution on a sponge."

Thanks for the clarification. I wanted to try some plain water on a dampened microfiber cloth, but I didn't want to touch it until I was sure it was safe to do. Both woofers have now been cleaned. The midrange on one speaker was already free from dust. The other midrange was very dusty from, I'm assuming, being kept in a dusty place without the speaker grill in place protecting it. I dusted it off and used a vacuum with the brush attachment to try and clean it further, but it still had a great deal of dust discoloration. I used a slightly damp cloth to remove much of the surface dust. Both tweeter caps were severely dented and I used a vacuum nozzle to pull out most of the dents. (I was aware of that solution and I have done it before on other speakers, thanks Kent)

One of the speaker grill frames is damaged and I'm in the process of trying to repair it. The other was intact and in good shape so I replaced the speaker grill with new cloth. See photos.

The repaired equalizer arrives on Tuesday and I'm hoping to have the grill frame repaired with a new grill cloth by then. I'll report out with my impressions after a few days of listening to the Thiel's, both with and without the equalizer.

BTW, I tried a new approach to replacing speaker cloth from a Youtube video I saw and it's working very well. I've never been really happy about how my grill replacements have turned out and I shy away from doing them because of that. The video suggested using a specific brand of double faced tape to attach the cloth to the grill frame and it worked really well. The name of the tape is Tesa and it's available on Amazon (Tesa 1/2 inch 4965 Double-coated tape) I put the 1/2 inch tape all the way around the grill frame and secured the grill cloth to it. The video suggested that the tape alone was all that was needed, and truth be told, it was pretty secure. But for added safety I fastened some of the extra fabric beyond the tape using 3M Super 77 adhesive. (I wear a belt and suspenders...) Very secure. Easy to do. No staples needed. I wish I knew about this approach years ago.

 

 

[Norman Nicolai]

I finally finished working on the Thiels. As per my previous post, the upper left grill frame was shattered on one of the speakers. It took me a while to figure out how to repair it. I gave up on trying to fabricate a completely new replacement piece, like in the photo from my previous post. I figured my best bet was to try an incorporate the three broken pieces into the replacement, and that seems to have worked.

I glued the pieces back together to the frame, and then supported the glued remnants with braces that overlapped the glued joints.  I had to fabricate almost all of the horizontal top piece and supported that with braces also. After all the glued pieces set, I filled in the joints with Plastic Wood, sanded them smooth after they dried, and then painted everything black. When the paint was completely dry, I stretched the grill cloth over the frame and secured it using double sided tape and 3M Super 77 adhesive. (Many thanks to JKent for recommending 3M Super 77 Adhesive for some of my other projects. It's been a really good addition to my tool repertory.) The last photo is of the finished speaker with the new frame and grill cloth. (Of al the speaker cabinet projects I have taken on, I am most proud of this one...)

I started using the dedicated Thiel equalizer with my Mitsubishi DA-A10 power amplifier and Conrad Johnson PV10 preamp about a week ago when I got it back from Ben Hase at SkyFi Audio. The equalizer is wired through the Tape Monitor function. The difference with the equalizer is subtle, but you can definitely hear it during musical pieces on instruments below 70 Hz, which is where it is supposed to provide boost. Now that I'm no longer listening to the speakers with my garage system and have them hooked up my main system, I'm really impressed. I've been switching back and forth between the Thiels and what I consider my reference speakers, AR-91's. The Thiels go a little bit deeper, have a slightly better "soundstage", and are a brighter and less "neutral" than the 91's, and I'm really torn between which speaker system I now prefer. The bottom line is that I would hate to part with them and have gotten attached to them, so I'm still switching back and forth with the 91's. The thing is, I only have one power amp that is capable of driving them, the DA-A10, since they require a good deal of power and are rated at 4 ohms, just like the AR-91's, so they're stuck in my basement. Every other power amp or receiver that I own is tubed and rated between 20-35 WPC, and I use them with smaller speakers throughout my house, largely due to WAF. I guess there really is an advantage to high-power SS amps...

 

 

 

I 

[Aadams]

On 9/21/2023 at 5:37 PM, Norman Nicolai said:

I've been switching back and forth between the Thiels and what I consider my reference speakers, AR-91's. The Thiels go a little bit deeper, have a slightly better "soundstage", and are a brighter and less "neutral" than the 91's, and I'm really torn between which speaker system I now prefer.

On 9/21/2023 at 5:37 PM, Norman Nicolai said:

 

If you decide to dump the 91s place the first ad here at CSP, please.

[Norman Nicolai]

I hope I didn’t give the wrong impression about my AR-91’s. I still consider them my “reference” speakers and they are the speakers that I continue to measure all other speakers by. I would never dream of parting with them. It’s just that I now have another set of speakers that I enjoy listening to as much as them. My 91’s are not for sale.

One thing I should mention about both the AR-91’s and the Thiel CS 3.5k’s: I’m not crazy about the way they both look. I remember a thread here on CSP about someone who preferred the sound of the AR-91’s, but the look of the AR-3a’s and started a project to incorporate the AR-91 drivers into a 3a cabinet. That’s something I could see myself trying to do when I have more experience working on speakers. Part of the issue is black speaker cloth and its prominence on modern speakers. I’m just not that crazy about that look and have replaced the black cloth on my walnut veneer EPI M100’s with white linen. (And they look absolutely great in my dining room, thank you…) Aside from the black speaker cloth, the modern looking AR-91 cabinets leave me cold, lower quality walnut veneer compared to the 3a’s, notwithstanding. The workmanship on the Thiel’s oak cabinets is first rate, and their angled design is a function of their “coherent source” concept, but I still prefer the look of traditional speakers with walnut veneer.